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-rw-r--r--fs/namei.c2454
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diff --git a/fs/namei.c b/fs/namei.c
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+++ b/fs/namei.c
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+/*
+ * linux/fs/namei.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+/*
+ * Some corrections by tytso.
+ */
+
+/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
+ * lookup logic.
+ */
+/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/quotaops.h>
+#include <linux/pagemap.h>
+#include <linux/dnotify.h>
+#include <linux/smp_lock.h>
+#include <linux/personality.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/mount.h>
+#include <linux/audit.h>
+#include <asm/namei.h>
+#include <asm/uaccess.h>
+
+#define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
+
+/* [Feb-1997 T. Schoebel-Theuer]
+ * Fundamental changes in the pathname lookup mechanisms (namei)
+ * were necessary because of omirr. The reason is that omirr needs
+ * to know the _real_ pathname, not the user-supplied one, in case
+ * of symlinks (and also when transname replacements occur).
+ *
+ * The new code replaces the old recursive symlink resolution with
+ * an iterative one (in case of non-nested symlink chains). It does
+ * this with calls to <fs>_follow_link().
+ * As a side effect, dir_namei(), _namei() and follow_link() are now
+ * replaced with a single function lookup_dentry() that can handle all
+ * the special cases of the former code.
+ *
+ * With the new dcache, the pathname is stored at each inode, at least as
+ * long as the refcount of the inode is positive. As a side effect, the
+ * size of the dcache depends on the inode cache and thus is dynamic.
+ *
+ * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
+ * resolution to correspond with current state of the code.
+ *
+ * Note that the symlink resolution is not *completely* iterative.
+ * There is still a significant amount of tail- and mid- recursion in
+ * the algorithm. Also, note that <fs>_readlink() is not used in
+ * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
+ * may return different results than <fs>_follow_link(). Many virtual
+ * filesystems (including /proc) exhibit this behavior.
+ */
+
+/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
+ * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
+ * and the name already exists in form of a symlink, try to create the new
+ * name indicated by the symlink. The old code always complained that the
+ * name already exists, due to not following the symlink even if its target
+ * is nonexistent. The new semantics affects also mknod() and link() when
+ * the name is a symlink pointing to a non-existant name.
+ *
+ * I don't know which semantics is the right one, since I have no access
+ * to standards. But I found by trial that HP-UX 9.0 has the full "new"
+ * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
+ * "old" one. Personally, I think the new semantics is much more logical.
+ * Note that "ln old new" where "new" is a symlink pointing to a non-existing
+ * file does succeed in both HP-UX and SunOs, but not in Solaris
+ * and in the old Linux semantics.
+ */
+
+/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
+ * semantics. See the comments in "open_namei" and "do_link" below.
+ *
+ * [10-Sep-98 Alan Modra] Another symlink change.
+ */
+
+/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
+ * inside the path - always follow.
+ * in the last component in creation/removal/renaming - never follow.
+ * if LOOKUP_FOLLOW passed - follow.
+ * if the pathname has trailing slashes - follow.
+ * otherwise - don't follow.
+ * (applied in that order).
+ *
+ * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
+ * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
+ * During the 2.4 we need to fix the userland stuff depending on it -
+ * hopefully we will be able to get rid of that wart in 2.5. So far only
+ * XEmacs seems to be relying on it...
+ */
+/*
+ * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
+ * implemented. Let's see if raised priority of ->s_vfs_rename_sem gives
+ * any extra contention...
+ */
+
+/* In order to reduce some races, while at the same time doing additional
+ * checking and hopefully speeding things up, we copy filenames to the
+ * kernel data space before using them..
+ *
+ * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
+ * PATH_MAX includes the nul terminator --RR.
+ */
+static inline int do_getname(const char __user *filename, char *page)
+{
+ int retval;
+ unsigned long len = PATH_MAX;
+
+ if (!segment_eq(get_fs(), KERNEL_DS)) {
+ if ((unsigned long) filename >= TASK_SIZE)
+ return -EFAULT;
+ if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
+ len = TASK_SIZE - (unsigned long) filename;
+ }
+
+ retval = strncpy_from_user(page, filename, len);
+ if (retval > 0) {
+ if (retval < len)
+ return 0;
+ return -ENAMETOOLONG;
+ } else if (!retval)
+ retval = -ENOENT;
+ return retval;
+}
+
+char * getname(const char __user * filename)
+{
+ char *tmp, *result;
+
+ result = ERR_PTR(-ENOMEM);
+ tmp = __getname();
+ if (tmp) {
+ int retval = do_getname(filename, tmp);
+
+ result = tmp;
+ if (retval < 0) {
+ __putname(tmp);
+ result = ERR_PTR(retval);
+ }
+ }
+ audit_getname(result);
+ return result;
+}
+
+#ifdef CONFIG_AUDITSYSCALL
+void putname(const char *name)
+{
+ if (unlikely(current->audit_context))
+ audit_putname(name);
+ else
+ __putname(name);
+}
+EXPORT_SYMBOL(putname);
+#endif
+
+
+/**
+ * generic_permission - check for access rights on a Posix-like filesystem
+ * @inode: inode to check access rights for
+ * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ * @check_acl: optional callback to check for Posix ACLs
+ *
+ * Used to check for read/write/execute permissions on a file.
+ * We use "fsuid" for this, letting us set arbitrary permissions
+ * for filesystem access without changing the "normal" uids which
+ * are used for other things..
+ */
+int generic_permission(struct inode *inode, int mask,
+ int (*check_acl)(struct inode *inode, int mask))
+{
+ umode_t mode = inode->i_mode;
+
+ if (current->fsuid == inode->i_uid)
+ mode >>= 6;
+ else {
+ if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
+ int error = check_acl(inode, mask);
+ if (error == -EACCES)
+ goto check_capabilities;
+ else if (error != -EAGAIN)
+ return error;
+ }
+
+ if (in_group_p(inode->i_gid))
+ mode >>= 3;
+ }
+
+ /*
+ * If the DACs are ok we don't need any capability check.
+ */
+ if (((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask))
+ return 0;
+
+ check_capabilities:
+ /*
+ * Read/write DACs are always overridable.
+ * Executable DACs are overridable if at least one exec bit is set.
+ */
+ if (!(mask & MAY_EXEC) ||
+ (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
+ if (capable(CAP_DAC_OVERRIDE))
+ return 0;
+
+ /*
+ * Searching includes executable on directories, else just read.
+ */
+ if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
+ if (capable(CAP_DAC_READ_SEARCH))
+ return 0;
+
+ return -EACCES;
+}
+
+int permission(struct inode *inode, int mask, struct nameidata *nd)
+{
+ int retval, submask;
+
+ if (mask & MAY_WRITE) {
+ umode_t mode = inode->i_mode;
+
+ /*
+ * Nobody gets write access to a read-only fs.
+ */
+ if (IS_RDONLY(inode) &&
+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+ return -EROFS;
+
+ /*
+ * Nobody gets write access to an immutable file.
+ */
+ if (IS_IMMUTABLE(inode))
+ return -EACCES;
+ }
+
+
+ /* Ordinary permission routines do not understand MAY_APPEND. */
+ submask = mask & ~MAY_APPEND;
+ if (inode->i_op && inode->i_op->permission)
+ retval = inode->i_op->permission(inode, submask, nd);
+ else
+ retval = generic_permission(inode, submask, NULL);
+ if (retval)
+ return retval;
+
+ return security_inode_permission(inode, mask, nd);
+}
+
+/*
+ * get_write_access() gets write permission for a file.
+ * put_write_access() releases this write permission.
+ * This is used for regular files.
+ * We cannot support write (and maybe mmap read-write shared) accesses and
+ * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
+ * can have the following values:
+ * 0: no writers, no VM_DENYWRITE mappings
+ * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
+ * > 0: (i_writecount) users are writing to the file.
+ *
+ * Normally we operate on that counter with atomic_{inc,dec} and it's safe
+ * except for the cases where we don't hold i_writecount yet. Then we need to
+ * use {get,deny}_write_access() - these functions check the sign and refuse
+ * to do the change if sign is wrong. Exclusion between them is provided by
+ * the inode->i_lock spinlock.
+ */
+
+int get_write_access(struct inode * inode)
+{
+ spin_lock(&inode->i_lock);
+ if (atomic_read(&inode->i_writecount) < 0) {
+ spin_unlock(&inode->i_lock);
+ return -ETXTBSY;
+ }
+ atomic_inc(&inode->i_writecount);
+ spin_unlock(&inode->i_lock);
+
+ return 0;
+}
+
+int deny_write_access(struct file * file)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+
+ spin_lock(&inode->i_lock);
+ if (atomic_read(&inode->i_writecount) > 0) {
+ spin_unlock(&inode->i_lock);
+ return -ETXTBSY;
+ }
+ atomic_dec(&inode->i_writecount);
+ spin_unlock(&inode->i_lock);
+
+ return 0;
+}
+
+void path_release(struct nameidata *nd)
+{
+ dput(nd->dentry);
+ mntput(nd->mnt);
+}
+
+/*
+ * umount() mustn't call path_release()/mntput() as that would clear
+ * mnt_expiry_mark
+ */
+void path_release_on_umount(struct nameidata *nd)
+{
+ dput(nd->dentry);
+ _mntput(nd->mnt);
+}
+
+/*
+ * Internal lookup() using the new generic dcache.
+ * SMP-safe
+ */
+static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
+{
+ struct dentry * dentry = __d_lookup(parent, name);
+
+ /* lockess __d_lookup may fail due to concurrent d_move()
+ * in some unrelated directory, so try with d_lookup
+ */
+ if (!dentry)
+ dentry = d_lookup(parent, name);
+
+ if (dentry && dentry->d_op && dentry->d_op->d_revalidate) {
+ if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) {
+ dput(dentry);
+ dentry = NULL;
+ }
+ }
+ return dentry;
+}
+
+/*
+ * Short-cut version of permission(), for calling by
+ * path_walk(), when dcache lock is held. Combines parts
+ * of permission() and generic_permission(), and tests ONLY for
+ * MAY_EXEC permission.
+ *
+ * If appropriate, check DAC only. If not appropriate, or
+ * short-cut DAC fails, then call permission() to do more
+ * complete permission check.
+ */
+static inline int exec_permission_lite(struct inode *inode,
+ struct nameidata *nd)
+{
+ umode_t mode = inode->i_mode;
+
+ if (inode->i_op && inode->i_op->permission)
+ return -EAGAIN;
+
+ if (current->fsuid == inode->i_uid)
+ mode >>= 6;
+ else if (in_group_p(inode->i_gid))
+ mode >>= 3;
+
+ if (mode & MAY_EXEC)
+ goto ok;
+
+ if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE))
+ goto ok;
+
+ if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE))
+ goto ok;
+
+ if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH))
+ goto ok;
+
+ return -EACCES;
+ok:
+ return security_inode_permission(inode, MAY_EXEC, nd);
+}
+
+/*
+ * This is called when everything else fails, and we actually have
+ * to go to the low-level filesystem to find out what we should do..
+ *
+ * We get the directory semaphore, and after getting that we also
+ * make sure that nobody added the entry to the dcache in the meantime..
+ * SMP-safe
+ */
+static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
+{
+ struct dentry * result;
+ struct inode *dir = parent->d_inode;
+
+ down(&dir->i_sem);
+ /*
+ * First re-do the cached lookup just in case it was created
+ * while we waited for the directory semaphore..
+ *
+ * FIXME! This could use version numbering or similar to
+ * avoid unnecessary cache lookups.
+ *
+ * The "dcache_lock" is purely to protect the RCU list walker
+ * from concurrent renames at this point (we mustn't get false
+ * negatives from the RCU list walk here, unlike the optimistic
+ * fast walk).
+ *
+ * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
+ */
+ result = d_lookup(parent, name);
+ if (!result) {
+ struct dentry * dentry = d_alloc(parent, name);
+ result = ERR_PTR(-ENOMEM);
+ if (dentry) {
+ result = dir->i_op->lookup(dir, dentry, nd);
+ if (result)
+ dput(dentry);
+ else
+ result = dentry;
+ }
+ up(&dir->i_sem);
+ return result;
+ }
+
+ /*
+ * Uhhuh! Nasty case: the cache was re-populated while
+ * we waited on the semaphore. Need to revalidate.
+ */
+ up(&dir->i_sem);
+ if (result->d_op && result->d_op->d_revalidate) {
+ if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) {
+ dput(result);
+ result = ERR_PTR(-ENOENT);
+ }
+ }
+ return result;
+}
+
+static int __emul_lookup_dentry(const char *, struct nameidata *);
+
+/* SMP-safe */
+static inline int
+walk_init_root(const char *name, struct nameidata *nd)
+{
+ read_lock(&current->fs->lock);
+ if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
+ nd->mnt = mntget(current->fs->altrootmnt);
+ nd->dentry = dget(current->fs->altroot);
+ read_unlock(&current->fs->lock);
+ if (__emul_lookup_dentry(name,nd))
+ return 0;
+ read_lock(&current->fs->lock);
+ }
+ nd->mnt = mntget(current->fs->rootmnt);
+ nd->dentry = dget(current->fs->root);
+ read_unlock(&current->fs->lock);
+ return 1;
+}
+
+static inline int __vfs_follow_link(struct nameidata *nd, const char *link)
+{
+ int res = 0;
+ char *name;
+ if (IS_ERR(link))
+ goto fail;
+
+ if (*link == '/') {
+ path_release(nd);
+ if (!walk_init_root(link, nd))
+ /* weird __emul_prefix() stuff did it */
+ goto out;
+ }
+ res = link_path_walk(link, nd);
+out:
+ if (nd->depth || res || nd->last_type!=LAST_NORM)
+ return res;
+ /*
+ * If it is an iterative symlinks resolution in open_namei() we
+ * have to copy the last component. And all that crap because of
+ * bloody create() on broken symlinks. Furrfu...
+ */
+ name = __getname();
+ if (unlikely(!name)) {
+ path_release(nd);
+ return -ENOMEM;
+ }
+ strcpy(name, nd->last.name);
+ nd->last.name = name;
+ return 0;
+fail:
+ path_release(nd);
+ return PTR_ERR(link);
+}
+
+static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ int error;
+
+ touch_atime(nd->mnt, dentry);
+ nd_set_link(nd, NULL);
+ error = dentry->d_inode->i_op->follow_link(dentry, nd);
+ if (!error) {
+ char *s = nd_get_link(nd);
+ if (s)
+ error = __vfs_follow_link(nd, s);
+ if (dentry->d_inode->i_op->put_link)
+ dentry->d_inode->i_op->put_link(dentry, nd);
+ }
+
+ return error;
+}
+
+/*
+ * This limits recursive symlink follows to 8, while
+ * limiting consecutive symlinks to 40.
+ *
+ * Without that kind of total limit, nasty chains of consecutive
+ * symlinks can cause almost arbitrarily long lookups.
+ */
+static inline int do_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ int err = -ELOOP;
+ if (current->link_count >= MAX_NESTED_LINKS)
+ goto loop;
+ if (current->total_link_count >= 40)
+ goto loop;
+ BUG_ON(nd->depth >= MAX_NESTED_LINKS);
+ cond_resched();
+ err = security_inode_follow_link(dentry, nd);
+ if (err)
+ goto loop;
+ current->link_count++;
+ current->total_link_count++;
+ nd->depth++;
+ err = __do_follow_link(dentry, nd);
+ current->link_count--;
+ nd->depth--;
+ return err;
+loop:
+ path_release(nd);
+ return err;
+}
+
+int follow_up(struct vfsmount **mnt, struct dentry **dentry)
+{
+ struct vfsmount *parent;
+ struct dentry *mountpoint;
+ spin_lock(&vfsmount_lock);
+ parent=(*mnt)->mnt_parent;
+ if (parent == *mnt) {
+ spin_unlock(&vfsmount_lock);
+ return 0;
+ }
+ mntget(parent);
+ mountpoint=dget((*mnt)->mnt_mountpoint);
+ spin_unlock(&vfsmount_lock);
+ dput(*dentry);
+ *dentry = mountpoint;
+ mntput(*mnt);
+ *mnt = parent;
+ return 1;
+}
+
+/* no need for dcache_lock, as serialization is taken care in
+ * namespace.c
+ */
+static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)
+{
+ int res = 0;
+ while (d_mountpoint(*dentry)) {
+ struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
+ if (!mounted)
+ break;
+ mntput(*mnt);
+ *mnt = mounted;
+ dput(*dentry);
+ *dentry = dget(mounted->mnt_root);
+ res = 1;
+ }
+ return res;
+}
+
+/* no need for dcache_lock, as serialization is taken care in
+ * namespace.c
+ */
+static inline int __follow_down(struct vfsmount **mnt, struct dentry **dentry)
+{
+ struct vfsmount *mounted;
+
+ mounted = lookup_mnt(*mnt, *dentry);
+ if (mounted) {
+ mntput(*mnt);
+ *mnt = mounted;
+ dput(*dentry);
+ *dentry = dget(mounted->mnt_root);
+ return 1;
+ }
+ return 0;
+}
+
+int follow_down(struct vfsmount **mnt, struct dentry **dentry)
+{
+ return __follow_down(mnt,dentry);
+}
+
+static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry)
+{
+ while(1) {
+ struct vfsmount *parent;
+ struct dentry *old = *dentry;
+
+ read_lock(&current->fs->lock);
+ if (*dentry == current->fs->root &&
+ *mnt == current->fs->rootmnt) {
+ read_unlock(&current->fs->lock);
+ break;
+ }
+ read_unlock(&current->fs->lock);
+ spin_lock(&dcache_lock);
+ if (*dentry != (*mnt)->mnt_root) {
+ *dentry = dget((*dentry)->d_parent);
+ spin_unlock(&dcache_lock);
+ dput(old);
+ break;
+ }
+ spin_unlock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
+ parent = (*mnt)->mnt_parent;
+ if (parent == *mnt) {
+ spin_unlock(&vfsmount_lock);
+ break;
+ }
+ mntget(parent);
+ *dentry = dget((*mnt)->mnt_mountpoint);
+ spin_unlock(&vfsmount_lock);
+ dput(old);
+ mntput(*mnt);
+ *mnt = parent;
+ }
+ follow_mount(mnt, dentry);
+}
+
+struct path {
+ struct vfsmount *mnt;
+ struct dentry *dentry;
+};
+
+/*
+ * It's more convoluted than I'd like it to be, but... it's still fairly
+ * small and for now I'd prefer to have fast path as straight as possible.
+ * It _is_ time-critical.
+ */
+static int do_lookup(struct nameidata *nd, struct qstr *name,
+ struct path *path)
+{
+ struct vfsmount *mnt = nd->mnt;
+ struct dentry *dentry = __d_lookup(nd->dentry, name);
+
+ if (!dentry)
+ goto need_lookup;
+ if (dentry->d_op && dentry->d_op->d_revalidate)
+ goto need_revalidate;
+done:
+ path->mnt = mnt;
+ path->dentry = dentry;
+ return 0;
+
+need_lookup:
+ dentry = real_lookup(nd->dentry, name, nd);
+ if (IS_ERR(dentry))
+ goto fail;
+ goto done;
+
+need_revalidate:
+ if (dentry->d_op->d_revalidate(dentry, nd))
+ goto done;
+ if (d_invalidate(dentry))
+ goto done;
+ dput(dentry);
+ goto need_lookup;
+
+fail:
+ return PTR_ERR(dentry);
+}
+
+/*
+ * Name resolution.
+ *
+ * This is the basic name resolution function, turning a pathname
+ * into the final dentry.
+ *
+ * We expect 'base' to be positive and a directory.
+ */
+static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
+{
+ struct path next;
+ struct inode *inode;
+ int err;
+ unsigned int lookup_flags = nd->flags;
+
+ while (*name=='/')
+ name++;
+ if (!*name)
+ goto return_reval;
+
+ inode = nd->dentry->d_inode;
+ if (nd->depth)
+ lookup_flags = LOOKUP_FOLLOW;
+
+ /* At this point we know we have a real path component. */
+ for(;;) {
+ unsigned long hash;
+ struct qstr this;
+ unsigned int c;
+
+ err = exec_permission_lite(inode, nd);
+ if (err == -EAGAIN) {
+ err = permission(inode, MAY_EXEC, nd);
+ }
+ if (err)
+ break;
+
+ this.name = name;
+ c = *(const unsigned char *)name;
+
+ hash = init_name_hash();
+ do {
+ name++;
+ hash = partial_name_hash(c, hash);
+ c = *(const unsigned char *)name;
+ } while (c && (c != '/'));
+ this.len = name - (const char *) this.name;
+ this.hash = end_name_hash(hash);
+
+ /* remove trailing slashes? */
+ if (!c)
+ goto last_component;
+ while (*++name == '/');
+ if (!*name)
+ goto last_with_slashes;
+
+ /*
+ * "." and ".." are special - ".." especially so because it has
+ * to be able to know about the current root directory and
+ * parent relationships.
+ */
+ if (this.name[0] == '.') switch (this.len) {
+ default:
+ break;
+ case 2:
+ if (this.name[1] != '.')
+ break;
+ follow_dotdot(&nd->mnt, &nd->dentry);
+ inode = nd->dentry->d_inode;
+ /* fallthrough */
+ case 1:
+ continue;
+ }
+ /*
+ * See if the low-level filesystem might want
+ * to use its own hash..
+ */
+ if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
+ err = nd->dentry->d_op->d_hash(nd->dentry, &this);
+ if (err < 0)
+ break;
+ }
+ nd->flags |= LOOKUP_CONTINUE;
+ /* This does the actual lookups.. */
+ err = do_lookup(nd, &this, &next);
+ if (err)
+ break;
+ /* Check mountpoints.. */
+ follow_mount(&next.mnt, &next.dentry);
+
+ err = -ENOENT;
+ inode = next.dentry->d_inode;
+ if (!inode)
+ goto out_dput;
+ err = -ENOTDIR;
+ if (!inode->i_op)
+ goto out_dput;
+
+ if (inode->i_op->follow_link) {
+ mntget(next.mnt);
+ err = do_follow_link(next.dentry, nd);
+ dput(next.dentry);
+ mntput(next.mnt);
+ if (err)
+ goto return_err;
+ err = -ENOENT;
+ inode = nd->dentry->d_inode;
+ if (!inode)
+ break;
+ err = -ENOTDIR;
+ if (!inode->i_op)
+ break;
+ } else {
+ dput(nd->dentry);
+ nd->mnt = next.mnt;
+ nd->dentry = next.dentry;
+ }
+ err = -ENOTDIR;
+ if (!inode->i_op->lookup)
+ break;
+ continue;
+ /* here ends the main loop */
+
+last_with_slashes:
+ lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+last_component:
+ nd->flags &= ~LOOKUP_CONTINUE;
+ if (lookup_flags & LOOKUP_PARENT)
+ goto lookup_parent;
+ if (this.name[0] == '.') switch (this.len) {
+ default:
+ break;
+ case 2:
+ if (this.name[1] != '.')
+ break;
+ follow_dotdot(&nd->mnt, &nd->dentry);
+ inode = nd->dentry->d_inode;
+ /* fallthrough */
+ case 1:
+ goto return_reval;
+ }
+ if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
+ err = nd->dentry->d_op->d_hash(nd->dentry, &this);
+ if (err < 0)
+ break;
+ }
+ err = do_lookup(nd, &this, &next);
+ if (err)
+ break;
+ follow_mount(&next.mnt, &next.dentry);
+ inode = next.dentry->d_inode;
+ if ((lookup_flags & LOOKUP_FOLLOW)
+ && inode && inode->i_op && inode->i_op->follow_link) {
+ mntget(next.mnt);
+ err = do_follow_link(next.dentry, nd);
+ dput(next.dentry);
+ mntput(next.mnt);
+ if (err)
+ goto return_err;
+ inode = nd->dentry->d_inode;
+ } else {
+ dput(nd->dentry);
+ nd->mnt = next.mnt;
+ nd->dentry = next.dentry;
+ }
+ err = -ENOENT;
+ if (!inode)
+ break;
+ if (lookup_flags & LOOKUP_DIRECTORY) {
+ err = -ENOTDIR;
+ if (!inode->i_op || !inode->i_op->lookup)
+ break;
+ }
+ goto return_base;
+lookup_parent:
+ nd->last = this;
+ nd->last_type = LAST_NORM;
+ if (this.name[0] != '.')
+ goto return_base;
+ if (this.len == 1)
+ nd->last_type = LAST_DOT;
+ else if (this.len == 2 && this.name[1] == '.')
+ nd->last_type = LAST_DOTDOT;
+ else
+ goto return_base;
+return_reval:
+ /*
+ * We bypassed the ordinary revalidation routines.
+ * We may need to check the cached dentry for staleness.
+ */
+ if (nd->dentry && nd->dentry->d_sb &&
+ (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
+ err = -ESTALE;
+ /* Note: we do not d_invalidate() */
+ if (!nd->dentry->d_op->d_revalidate(nd->dentry, nd))
+ break;
+ }
+return_base:
+ return 0;
+out_dput:
+ dput(next.dentry);
+ break;
+ }
+ path_release(nd);
+return_err:
+ return err;
+}
+
+/*
+ * Wrapper to retry pathname resolution whenever the underlying
+ * file system returns an ESTALE.
+ *
+ * Retry the whole path once, forcing real lookup requests
+ * instead of relying on the dcache.
+ */
+int fastcall link_path_walk(const char *name, struct nameidata *nd)
+{
+ struct nameidata save = *nd;
+ int result;
+
+ /* make sure the stuff we saved doesn't go away */
+ dget(save.dentry);
+ mntget(save.mnt);
+
+ result = __link_path_walk(name, nd);
+ if (result == -ESTALE) {
+ *nd = save;
+ dget(nd->dentry);
+ mntget(nd->mnt);
+ nd->flags |= LOOKUP_REVAL;
+ result = __link_path_walk(name, nd);
+ }
+
+ dput(save.dentry);
+ mntput(save.mnt);
+
+ return result;
+}
+
+int fastcall path_walk(const char * name, struct nameidata *nd)
+{
+ current->total_link_count = 0;
+ return link_path_walk(name, nd);
+}
+
+/* SMP-safe */
+/* returns 1 if everything is done */
+static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
+{
+ if (path_walk(name, nd))
+ return 0; /* something went wrong... */
+
+ if (!nd->dentry->d_inode || S_ISDIR(nd->dentry->d_inode->i_mode)) {
+ struct dentry *old_dentry = nd->dentry;
+ struct vfsmount *old_mnt = nd->mnt;
+ struct qstr last = nd->last;
+ int last_type = nd->last_type;
+ /*
+ * NAME was not found in alternate root or it's a directory. Try to find
+ * it in the normal root:
+ */
+ nd->last_type = LAST_ROOT;
+ read_lock(&current->fs->lock);
+ nd->mnt = mntget(current->fs->rootmnt);
+ nd->dentry = dget(current->fs->root);
+ read_unlock(&current->fs->lock);
+ if (path_walk(name, nd) == 0) {
+ if (nd->dentry->d_inode) {
+ dput(old_dentry);
+ mntput(old_mnt);
+ return 1;
+ }
+ path_release(nd);
+ }
+ nd->dentry = old_dentry;
+ nd->mnt = old_mnt;
+ nd->last = last;
+ nd->last_type = last_type;
+ }
+ return 1;
+}
+
+void set_fs_altroot(void)
+{
+ char *emul = __emul_prefix();
+ struct nameidata nd;
+ struct vfsmount *mnt = NULL, *oldmnt;
+ struct dentry *dentry = NULL, *olddentry;
+ int err;
+
+ if (!emul)
+ goto set_it;
+ err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd);
+ if (!err) {
+ mnt = nd.mnt;
+ dentry = nd.dentry;
+ }
+set_it:
+ write_lock(&current->fs->lock);
+ oldmnt = current->fs->altrootmnt;
+ olddentry = current->fs->altroot;
+ current->fs->altrootmnt = mnt;
+ current->fs->altroot = dentry;
+ write_unlock(&current->fs->lock);
+ if (olddentry) {
+ dput(olddentry);
+ mntput(oldmnt);
+ }
+}
+
+int fastcall path_lookup(const char *name, unsigned int flags, struct nameidata *nd)
+{
+ int retval;
+
+ nd->last_type = LAST_ROOT; /* if there are only slashes... */
+ nd->flags = flags;
+ nd->depth = 0;
+
+ read_lock(&current->fs->lock);
+ if (*name=='/') {
+ if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
+ nd->mnt = mntget(current->fs->altrootmnt);
+ nd->dentry = dget(current->fs->altroot);
+ read_unlock(&current->fs->lock);
+ if (__emul_lookup_dentry(name,nd))
+ return 0;
+ read_lock(&current->fs->lock);
+ }
+ nd->mnt = mntget(current->fs->rootmnt);
+ nd->dentry = dget(current->fs->root);
+ } else {
+ nd->mnt = mntget(current->fs->pwdmnt);
+ nd->dentry = dget(current->fs->pwd);
+ }
+ read_unlock(&current->fs->lock);
+ current->total_link_count = 0;
+ retval = link_path_walk(name, nd);
+ if (unlikely(current->audit_context
+ && nd && nd->dentry && nd->dentry->d_inode))
+ audit_inode(name, nd->dentry->d_inode);
+ return retval;
+}
+
+/*
+ * Restricted form of lookup. Doesn't follow links, single-component only,
+ * needs parent already locked. Doesn't follow mounts.
+ * SMP-safe.
+ */
+static struct dentry * __lookup_hash(struct qstr *name, struct dentry * base, struct nameidata *nd)
+{
+ struct dentry * dentry;
+ struct inode *inode;
+ int err;
+
+ inode = base->d_inode;
+ err = permission(inode, MAY_EXEC, nd);
+ dentry = ERR_PTR(err);
+ if (err)
+ goto out;
+
+ /*
+ * See if the low-level filesystem might want
+ * to use its own hash..
+ */
+ if (base->d_op && base->d_op->d_hash) {
+ err = base->d_op->d_hash(base, name);
+ dentry = ERR_PTR(err);
+ if (err < 0)
+ goto out;
+ }
+
+ dentry = cached_lookup(base, name, nd);
+ if (!dentry) {
+ struct dentry *new = d_alloc(base, name);
+ dentry = ERR_PTR(-ENOMEM);
+ if (!new)
+ goto out;
+ dentry = inode->i_op->lookup(inode, new, nd);
+ if (!dentry)
+ dentry = new;
+ else
+ dput(new);
+ }
+out:
+ return dentry;
+}
+
+struct dentry * lookup_hash(struct qstr *name, struct dentry * base)
+{
+ return __lookup_hash(name, base, NULL);
+}
+
+/* SMP-safe */
+struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
+{
+ unsigned long hash;
+ struct qstr this;
+ unsigned int c;
+
+ this.name = name;
+ this.len = len;
+ if (!len)
+ goto access;
+
+ hash = init_name_hash();
+ while (len--) {
+ c = *(const unsigned char *)name++;
+ if (c == '/' || c == '\0')
+ goto access;
+ hash = partial_name_hash(c, hash);
+ }
+ this.hash = end_name_hash(hash);
+
+ return lookup_hash(&this, base);
+access:
+ return ERR_PTR(-EACCES);
+}
+
+/*
+ * namei()
+ *
+ * is used by most simple commands to get the inode of a specified name.
+ * Open, link etc use their own routines, but this is enough for things
+ * like 'chmod' etc.
+ *
+ * namei exists in two versions: namei/lnamei. The only difference is
+ * that namei follows links, while lnamei does not.
+ * SMP-safe
+ */
+int fastcall __user_walk(const char __user *name, unsigned flags, struct nameidata *nd)
+{
+ char *tmp = getname(name);
+ int err = PTR_ERR(tmp);
+
+ if (!IS_ERR(tmp)) {
+ err = path_lookup(tmp, flags, nd);
+ putname(tmp);
+ }
+ return err;
+}
+
+/*
+ * It's inline, so penalty for filesystems that don't use sticky bit is
+ * minimal.
+ */
+static inline int check_sticky(struct inode *dir, struct inode *inode)
+{
+ if (!(dir->i_mode & S_ISVTX))
+ return 0;
+ if (inode->i_uid == current->fsuid)
+ return 0;
+ if (dir->i_uid == current->fsuid)
+ return 0;
+ return !capable(CAP_FOWNER);
+}
+
+/*
+ * Check whether we can remove a link victim from directory dir, check
+ * whether the type of victim is right.
+ * 1. We can't do it if dir is read-only (done in permission())
+ * 2. We should have write and exec permissions on dir
+ * 3. We can't remove anything from append-only dir
+ * 4. We can't do anything with immutable dir (done in permission())
+ * 5. If the sticky bit on dir is set we should either
+ * a. be owner of dir, or
+ * b. be owner of victim, or
+ * c. have CAP_FOWNER capability
+ * 6. If the victim is append-only or immutable we can't do antyhing with
+ * links pointing to it.
+ * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
+ * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
+ * 9. We can't remove a root or mountpoint.
+ * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
+ * nfs_async_unlink().
+ */
+static inline int may_delete(struct inode *dir,struct dentry *victim,int isdir)
+{
+ int error;
+
+ if (!victim->d_inode)
+ return -ENOENT;
+
+ BUG_ON(victim->d_parent->d_inode != dir);
+
+ error = permission(dir,MAY_WRITE | MAY_EXEC, NULL);
+ if (error)
+ return error;
+ if (IS_APPEND(dir))
+ return -EPERM;
+ if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
+ IS_IMMUTABLE(victim->d_inode))
+ return -EPERM;
+ if (isdir) {
+ if (!S_ISDIR(victim->d_inode->i_mode))
+ return -ENOTDIR;
+ if (IS_ROOT(victim))
+ return -EBUSY;
+ } else if (S_ISDIR(victim->d_inode->i_mode))
+ return -EISDIR;
+ if (IS_DEADDIR(dir))
+ return -ENOENT;
+ if (victim->d_flags & DCACHE_NFSFS_RENAMED)
+ return -EBUSY;
+ return 0;
+}
+
+/* Check whether we can create an object with dentry child in directory
+ * dir.
+ * 1. We can't do it if child already exists (open has special treatment for
+ * this case, but since we are inlined it's OK)
+ * 2. We can't do it if dir is read-only (done in permission())
+ * 3. We should have write and exec permissions on dir
+ * 4. We can't do it if dir is immutable (done in permission())
+ */
+static inline int may_create(struct inode *dir, struct dentry *child,
+ struct nameidata *nd)
+{
+ if (child->d_inode)
+ return -EEXIST;
+ if (IS_DEADDIR(dir))
+ return -ENOENT;
+ return permission(dir,MAY_WRITE | MAY_EXEC, nd);
+}
+
+/*
+ * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security
+ * reasons.
+ *
+ * O_DIRECTORY translates into forcing a directory lookup.
+ */
+static inline int lookup_flags(unsigned int f)
+{
+ unsigned long retval = LOOKUP_FOLLOW;
+
+ if (f & O_NOFOLLOW)
+ retval &= ~LOOKUP_FOLLOW;
+
+ if ((f & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
+ retval &= ~LOOKUP_FOLLOW;
+
+ if (f & O_DIRECTORY)
+ retval |= LOOKUP_DIRECTORY;
+
+ return retval;
+}
+
+/*
+ * p1 and p2 should be directories on the same fs.
+ */
+struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
+{
+ struct dentry *p;
+
+ if (p1 == p2) {
+ down(&p1->d_inode->i_sem);
+ return NULL;
+ }
+
+ down(&p1->d_inode->i_sb->s_vfs_rename_sem);
+
+ for (p = p1; p->d_parent != p; p = p->d_parent) {
+ if (p->d_parent == p2) {
+ down(&p2->d_inode->i_sem);
+ down(&p1->d_inode->i_sem);
+ return p;
+ }
+ }
+
+ for (p = p2; p->d_parent != p; p = p->d_parent) {
+ if (p->d_parent == p1) {
+ down(&p1->d_inode->i_sem);
+ down(&p2->d_inode->i_sem);
+ return p;
+ }
+ }
+
+ down(&p1->d_inode->i_sem);
+ down(&p2->d_inode->i_sem);
+ return NULL;
+}
+
+void unlock_rename(struct dentry *p1, struct dentry *p2)
+{
+ up(&p1->d_inode->i_sem);
+ if (p1 != p2) {
+ up(&p2->d_inode->i_sem);
+ up(&p1->d_inode->i_sb->s_vfs_rename_sem);
+ }
+}
+
+int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
+ struct nameidata *nd)
+{
+ int error = may_create(dir, dentry, nd);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op || !dir->i_op->create)
+ return -EACCES; /* shouldn't it be ENOSYS? */
+ mode &= S_IALLUGO;
+ mode |= S_IFREG;
+ error = security_inode_create(dir, dentry, mode);
+ if (error)
+ return error;
+ DQUOT_INIT(dir);
+ error = dir->i_op->create(dir, dentry, mode, nd);
+ if (!error) {
+ inode_dir_notify(dir, DN_CREATE);
+ security_inode_post_create(dir, dentry, mode);
+ }
+ return error;
+}
+
+int may_open(struct nameidata *nd, int acc_mode, int flag)
+{
+ struct dentry *dentry = nd->dentry;
+ struct inode *inode = dentry->d_inode;
+ int error;
+
+ if (!inode)
+ return -ENOENT;
+
+ if (S_ISLNK(inode->i_mode))
+ return -ELOOP;
+
+ if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
+ return -EISDIR;
+
+ error = permission(inode, acc_mode, nd);
+ if (error)
+ return error;
+
+ /*
+ * FIFO's, sockets and device files are special: they don't
+ * actually live on the filesystem itself, and as such you
+ * can write to them even if the filesystem is read-only.
+ */
+ if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
+ flag &= ~O_TRUNC;
+ } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
+ if (nd->mnt->mnt_flags & MNT_NODEV)
+ return -EACCES;
+
+ flag &= ~O_TRUNC;
+ } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE))
+ return -EROFS;
+ /*
+ * An append-only file must be opened in append mode for writing.
+ */
+ if (IS_APPEND(inode)) {
+ if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
+ return -EPERM;
+ if (flag & O_TRUNC)
+ return -EPERM;
+ }
+
+ /* O_NOATIME can only be set by the owner or superuser */
+ if (flag & O_NOATIME)
+ if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
+ return -EPERM;
+
+ /*
+ * Ensure there are no outstanding leases on the file.
+ */
+ error = break_lease(inode, flag);
+ if (error)
+ return error;
+
+ if (flag & O_TRUNC) {
+ error = get_write_access(inode);
+ if (error)
+ return error;
+
+ /*
+ * Refuse to truncate files with mandatory locks held on them.
+ */
+ error = locks_verify_locked(inode);
+ if (!error) {
+ DQUOT_INIT(inode);
+
+ error = do_truncate(dentry, 0);
+ }
+ put_write_access(inode);
+ if (error)
+ return error;
+ } else
+ if (flag & FMODE_WRITE)
+ DQUOT_INIT(inode);
+
+ return 0;
+}
+
+/*
+ * open_namei()
+ *
+ * namei for open - this is in fact almost the whole open-routine.
+ *
+ * Note that the low bits of "flag" aren't the same as in the open
+ * system call - they are 00 - no permissions needed
+ * 01 - read permission needed
+ * 10 - write permission needed
+ * 11 - read/write permissions needed
+ * which is a lot more logical, and also allows the "no perm" needed
+ * for symlinks (where the permissions are checked later).
+ * SMP-safe
+ */
+int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
+{
+ int acc_mode, error = 0;
+ struct dentry *dentry;
+ struct dentry *dir;
+ int count = 0;
+
+ acc_mode = ACC_MODE(flag);
+
+ /* Allow the LSM permission hook to distinguish append
+ access from general write access. */
+ if (flag & O_APPEND)
+ acc_mode |= MAY_APPEND;
+
+ /* Fill in the open() intent data */
+ nd->intent.open.flags = flag;
+ nd->intent.open.create_mode = mode;
+
+ /*
+ * The simplest case - just a plain lookup.
+ */
+ if (!(flag & O_CREAT)) {
+ error = path_lookup(pathname, lookup_flags(flag)|LOOKUP_OPEN, nd);
+ if (error)
+ return error;
+ goto ok;
+ }
+
+ /*
+ * Create - we need to know the parent.
+ */
+ error = path_lookup(pathname, LOOKUP_PARENT|LOOKUP_OPEN|LOOKUP_CREATE, nd);
+ if (error)
+ return error;
+
+ /*
+ * We have the parent and last component. First of all, check
+ * that we are not asked to creat(2) an obvious directory - that
+ * will not do.
+ */
+ error = -EISDIR;
+ if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len])
+ goto exit;
+
+ dir = nd->dentry;
+ nd->flags &= ~LOOKUP_PARENT;
+ down(&dir->d_inode->i_sem);
+ dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+
+do_last:
+ error = PTR_ERR(dentry);
+ if (IS_ERR(dentry)) {
+ up(&dir->d_inode->i_sem);
+ goto exit;
+ }
+
+ /* Negative dentry, just create the file */
+ if (!dentry->d_inode) {
+ if (!IS_POSIXACL(dir->d_inode))
+ mode &= ~current->fs->umask;
+ error = vfs_create(dir->d_inode, dentry, mode, nd);
+ up(&dir->d_inode->i_sem);
+ dput(nd->dentry);
+ nd->dentry = dentry;
+ if (error)
+ goto exit;
+ /* Don't check for write permission, don't truncate */
+ acc_mode = 0;
+ flag &= ~O_TRUNC;
+ goto ok;
+ }
+
+ /*
+ * It already exists.
+ */
+ up(&dir->d_inode->i_sem);
+
+ error = -EEXIST;
+ if (flag & O_EXCL)
+ goto exit_dput;
+
+ if (d_mountpoint(dentry)) {
+ error = -ELOOP;
+ if (flag & O_NOFOLLOW)
+ goto exit_dput;
+ while (__follow_down(&nd->mnt,&dentry) && d_mountpoint(dentry));
+ }
+ error = -ENOENT;
+ if (!dentry->d_inode)
+ goto exit_dput;
+ if (dentry->d_inode->i_op && dentry->d_inode->i_op->follow_link)
+ goto do_link;
+
+ dput(nd->dentry);
+ nd->dentry = dentry;
+ error = -EISDIR;
+ if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode))
+ goto exit;
+ok:
+ error = may_open(nd, acc_mode, flag);
+ if (error)
+ goto exit;
+ return 0;
+
+exit_dput:
+ dput(dentry);
+exit:
+ path_release(nd);
+ return error;
+
+do_link:
+ error = -ELOOP;
+ if (flag & O_NOFOLLOW)
+ goto exit_dput;
+ /*
+ * This is subtle. Instead of calling do_follow_link() we do the
+ * thing by hands. The reason is that this way we have zero link_count
+ * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
+ * After that we have the parent and last component, i.e.
+ * we are in the same situation as after the first path_walk().
+ * Well, almost - if the last component is normal we get its copy
+ * stored in nd->last.name and we will have to putname() it when we
+ * are done. Procfs-like symlinks just set LAST_BIND.
+ */
+ nd->flags |= LOOKUP_PARENT;
+ error = security_inode_follow_link(dentry, nd);
+ if (error)
+ goto exit_dput;
+ error = __do_follow_link(dentry, nd);
+ dput(dentry);
+ if (error)
+ return error;
+ nd->flags &= ~LOOKUP_PARENT;
+ if (nd->last_type == LAST_BIND) {
+ dentry = nd->dentry;
+ goto ok;
+ }
+ error = -EISDIR;
+ if (nd->last_type != LAST_NORM)
+ goto exit;
+ if (nd->last.name[nd->last.len]) {
+ putname(nd->last.name);
+ goto exit;
+ }
+ error = -ELOOP;
+ if (count++==32) {
+ putname(nd->last.name);
+ goto exit;
+ }
+ dir = nd->dentry;
+ down(&dir->d_inode->i_sem);
+ dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+ putname(nd->last.name);
+ goto do_last;
+}
+
+/**
+ * lookup_create - lookup a dentry, creating it if it doesn't exist
+ * @nd: nameidata info
+ * @is_dir: directory flag
+ *
+ * Simple function to lookup and return a dentry and create it
+ * if it doesn't exist. Is SMP-safe.
+ */
+struct dentry *lookup_create(struct nameidata *nd, int is_dir)
+{
+ struct dentry *dentry;
+
+ down(&nd->dentry->d_inode->i_sem);
+ dentry = ERR_PTR(-EEXIST);
+ if (nd->last_type != LAST_NORM)
+ goto fail;
+ nd->flags &= ~LOOKUP_PARENT;
+ dentry = lookup_hash(&nd->last, nd->dentry);
+ if (IS_ERR(dentry))
+ goto fail;
+ if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
+ goto enoent;
+ return dentry;
+enoent:
+ dput(dentry);
+ dentry = ERR_PTR(-ENOENT);
+fail:
+ return dentry;
+}
+
+int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
+{
+ int error = may_create(dir, dentry, NULL);
+
+ if (error)
+ return error;
+
+ if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
+ return -EPERM;
+
+ if (!dir->i_op || !dir->i_op->mknod)
+ return -EPERM;
+
+ error = security_inode_mknod(dir, dentry, mode, dev);
+ if (error)
+ return error;
+
+ DQUOT_INIT(dir);
+ error = dir->i_op->mknod(dir, dentry, mode, dev);
+ if (!error) {
+ inode_dir_notify(dir, DN_CREATE);
+ security_inode_post_mknod(dir, dentry, mode, dev);
+ }
+ return error;
+}
+
+asmlinkage long sys_mknod(const char __user * filename, int mode, unsigned dev)
+{
+ int error = 0;
+ char * tmp;
+ struct dentry * dentry;
+ struct nameidata nd;
+
+ if (S_ISDIR(mode))
+ return -EPERM;
+ tmp = getname(filename);
+ if (IS_ERR(tmp))
+ return PTR_ERR(tmp);
+
+ error = path_lookup(tmp, LOOKUP_PARENT, &nd);
+ if (error)
+ goto out;
+ dentry = lookup_create(&nd, 0);
+ error = PTR_ERR(dentry);
+
+ if (!IS_POSIXACL(nd.dentry->d_inode))
+ mode &= ~current->fs->umask;
+ if (!IS_ERR(dentry)) {
+ switch (mode & S_IFMT) {
+ case 0: case S_IFREG:
+ error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
+ break;
+ case S_IFCHR: case S_IFBLK:
+ error = vfs_mknod(nd.dentry->d_inode,dentry,mode,
+ new_decode_dev(dev));
+ break;
+ case S_IFIFO: case S_IFSOCK:
+ error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
+ break;
+ case S_IFDIR:
+ error = -EPERM;
+ break;
+ default:
+ error = -EINVAL;
+ }
+ dput(dentry);
+ }
+ up(&nd.dentry->d_inode->i_sem);
+ path_release(&nd);
+out:
+ putname(tmp);
+
+ return error;
+}
+
+int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+ int error = may_create(dir, dentry, NULL);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op || !dir->i_op->mkdir)
+ return -EPERM;
+
+ mode &= (S_IRWXUGO|S_ISVTX);
+ error = security_inode_mkdir(dir, dentry, mode);
+ if (error)
+ return error;
+
+ DQUOT_INIT(dir);
+ error = dir->i_op->mkdir(dir, dentry, mode);
+ if (!error) {
+ inode_dir_notify(dir, DN_CREATE);
+ security_inode_post_mkdir(dir,dentry, mode);
+ }
+ return error;
+}
+
+asmlinkage long sys_mkdir(const char __user * pathname, int mode)
+{
+ int error = 0;
+ char * tmp;
+
+ tmp = getname(pathname);
+ error = PTR_ERR(tmp);
+ if (!IS_ERR(tmp)) {
+ struct dentry *dentry;
+ struct nameidata nd;
+
+ error = path_lookup(tmp, LOOKUP_PARENT, &nd);
+ if (error)
+ goto out;
+ dentry = lookup_create(&nd, 1);
+ error = PTR_ERR(dentry);
+ if (!IS_ERR(dentry)) {
+ if (!IS_POSIXACL(nd.dentry->d_inode))
+ mode &= ~current->fs->umask;
+ error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
+ dput(dentry);
+ }
+ up(&nd.dentry->d_inode->i_sem);
+ path_release(&nd);
+out:
+ putname(tmp);
+ }
+
+ return error;
+}
+
+/*
+ * We try to drop the dentry early: we should have
+ * a usage count of 2 if we're the only user of this
+ * dentry, and if that is true (possibly after pruning
+ * the dcache), then we drop the dentry now.
+ *
+ * A low-level filesystem can, if it choses, legally
+ * do a
+ *
+ * if (!d_unhashed(dentry))
+ * return -EBUSY;
+ *
+ * if it cannot handle the case of removing a directory
+ * that is still in use by something else..
+ */
+void dentry_unhash(struct dentry *dentry)
+{
+ dget(dentry);
+ if (atomic_read(&dentry->d_count))
+ shrink_dcache_parent(dentry);
+ spin_lock(&dcache_lock);
+ spin_lock(&dentry->d_lock);
+ if (atomic_read(&dentry->d_count) == 2)
+ __d_drop(dentry);
+ spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_lock);
+}
+
+int vfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ int error = may_delete(dir, dentry, 1);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op || !dir->i_op->rmdir)
+ return -EPERM;
+
+ DQUOT_INIT(dir);
+
+ down(&dentry->d_inode->i_sem);
+ dentry_unhash(dentry);
+ if (d_mountpoint(dentry))
+ error = -EBUSY;
+ else {
+ error = security_inode_rmdir(dir, dentry);
+ if (!error) {
+ error = dir->i_op->rmdir(dir, dentry);
+ if (!error)
+ dentry->d_inode->i_flags |= S_DEAD;
+ }
+ }
+ up(&dentry->d_inode->i_sem);
+ if (!error) {
+ inode_dir_notify(dir, DN_DELETE);
+ d_delete(dentry);
+ }
+ dput(dentry);
+
+ return error;
+}
+
+asmlinkage long sys_rmdir(const char __user * pathname)
+{
+ int error = 0;
+ char * name;
+ struct dentry *dentry;
+ struct nameidata nd;
+
+ name = getname(pathname);
+ if(IS_ERR(name))
+ return PTR_ERR(name);
+
+ error = path_lookup(name, LOOKUP_PARENT, &nd);
+ if (error)
+ goto exit;
+
+ switch(nd.last_type) {
+ case LAST_DOTDOT:
+ error = -ENOTEMPTY;
+ goto exit1;
+ case LAST_DOT:
+ error = -EINVAL;
+ goto exit1;
+ case LAST_ROOT:
+ error = -EBUSY;
+ goto exit1;
+ }
+ down(&nd.dentry->d_inode->i_sem);
+ dentry = lookup_hash(&nd.last, nd.dentry);
+ error = PTR_ERR(dentry);
+ if (!IS_ERR(dentry)) {
+ error = vfs_rmdir(nd.dentry->d_inode, dentry);
+ dput(dentry);
+ }
+ up(&nd.dentry->d_inode->i_sem);
+exit1:
+ path_release(&nd);
+exit:
+ putname(name);
+ return error;
+}
+
+int vfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+ int error = may_delete(dir, dentry, 0);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op || !dir->i_op->unlink)
+ return -EPERM;
+
+ DQUOT_INIT(dir);
+
+ down(&dentry->d_inode->i_sem);
+ if (d_mountpoint(dentry))
+ error = -EBUSY;
+ else {
+ error = security_inode_unlink(dir, dentry);
+ if (!error)
+ error = dir->i_op->unlink(dir, dentry);
+ }
+ up(&dentry->d_inode->i_sem);
+
+ /* We don't d_delete() NFS sillyrenamed files--they still exist. */
+ if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
+ d_delete(dentry);
+ inode_dir_notify(dir, DN_DELETE);
+ }
+ return error;
+}
+
+/*
+ * Make sure that the actual truncation of the file will occur outside its
+ * directory's i_sem. Truncate can take a long time if there is a lot of
+ * writeout happening, and we don't want to prevent access to the directory
+ * while waiting on the I/O.
+ */
+asmlinkage long sys_unlink(const char __user * pathname)
+{
+ int error = 0;
+ char * name;
+ struct dentry *dentry;
+ struct nameidata nd;
+ struct inode *inode = NULL;
+
+ name = getname(pathname);
+ if(IS_ERR(name))
+ return PTR_ERR(name);
+
+ error = path_lookup(name, LOOKUP_PARENT, &nd);
+ if (error)
+ goto exit;
+ error = -EISDIR;
+ if (nd.last_type != LAST_NORM)
+ goto exit1;
+ down(&nd.dentry->d_inode->i_sem);
+ dentry = lookup_hash(&nd.last, nd.dentry);
+ error = PTR_ERR(dentry);
+ if (!IS_ERR(dentry)) {
+ /* Why not before? Because we want correct error value */
+ if (nd.last.name[nd.last.len])
+ goto slashes;
+ inode = dentry->d_inode;
+ if (inode)
+ atomic_inc(&inode->i_count);
+ error = vfs_unlink(nd.dentry->d_inode, dentry);
+ exit2:
+ dput(dentry);
+ }
+ up(&nd.dentry->d_inode->i_sem);
+ if (inode)
+ iput(inode); /* truncate the inode here */
+exit1:
+ path_release(&nd);
+exit:
+ putname(name);
+ return error;
+
+slashes:
+ error = !dentry->d_inode ? -ENOENT :
+ S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
+ goto exit2;
+}
+
+int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname, int mode)
+{
+ int error = may_create(dir, dentry, NULL);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op || !dir->i_op->symlink)
+ return -EPERM;
+
+ error = security_inode_symlink(dir, dentry, oldname);
+ if (error)
+ return error;
+
+ DQUOT_INIT(dir);
+ error = dir->i_op->symlink(dir, dentry, oldname);
+ if (!error) {
+ inode_dir_notify(dir, DN_CREATE);
+ security_inode_post_symlink(dir, dentry, oldname);
+ }
+ return error;
+}
+
+asmlinkage long sys_symlink(const char __user * oldname, const char __user * newname)
+{
+ int error = 0;
+ char * from;
+ char * to;
+
+ from = getname(oldname);
+ if(IS_ERR(from))
+ return PTR_ERR(from);
+ to = getname(newname);
+ error = PTR_ERR(to);
+ if (!IS_ERR(to)) {
+ struct dentry *dentry;
+ struct nameidata nd;
+
+ error = path_lookup(to, LOOKUP_PARENT, &nd);
+ if (error)
+ goto out;
+ dentry = lookup_create(&nd, 0);
+ error = PTR_ERR(dentry);
+ if (!IS_ERR(dentry)) {
+ error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
+ dput(dentry);
+ }
+ up(&nd.dentry->d_inode->i_sem);
+ path_release(&nd);
+out:
+ putname(to);
+ }
+ putname(from);
+ return error;
+}
+
+int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
+{
+ struct inode *inode = old_dentry->d_inode;
+ int error;
+
+ if (!inode)
+ return -ENOENT;
+
+ error = may_create(dir, new_dentry, NULL);
+ if (error)
+ return error;
+
+ if (dir->i_sb != inode->i_sb)
+ return -EXDEV;
+
+ /*
+ * A link to an append-only or immutable file cannot be created.
+ */
+ if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
+ return -EPERM;
+ if (!dir->i_op || !dir->i_op->link)
+ return -EPERM;
+ if (S_ISDIR(old_dentry->d_inode->i_mode))
+ return -EPERM;
+
+ error = security_inode_link(old_dentry, dir, new_dentry);
+ if (error)
+ return error;
+
+ down(&old_dentry->d_inode->i_sem);
+ DQUOT_INIT(dir);
+ error = dir->i_op->link(old_dentry, dir, new_dentry);
+ up(&old_dentry->d_inode->i_sem);
+ if (!error) {
+ inode_dir_notify(dir, DN_CREATE);
+ security_inode_post_link(old_dentry, dir, new_dentry);
+ }
+ return error;
+}
+
+/*
+ * Hardlinks are often used in delicate situations. We avoid
+ * security-related surprises by not following symlinks on the
+ * newname. --KAB
+ *
+ * We don't follow them on the oldname either to be compatible
+ * with linux 2.0, and to avoid hard-linking to directories
+ * and other special files. --ADM
+ */
+asmlinkage long sys_link(const char __user * oldname, const char __user * newname)
+{
+ struct dentry *new_dentry;
+ struct nameidata nd, old_nd;
+ int error;
+ char * to;
+
+ to = getname(newname);
+ if (IS_ERR(to))
+ return PTR_ERR(to);
+
+ error = __user_walk(oldname, 0, &old_nd);
+ if (error)
+ goto exit;
+ error = path_lookup(to, LOOKUP_PARENT, &nd);
+ if (error)
+ goto out;
+ error = -EXDEV;
+ if (old_nd.mnt != nd.mnt)
+ goto out_release;
+ new_dentry = lookup_create(&nd, 0);
+ error = PTR_ERR(new_dentry);
+ if (!IS_ERR(new_dentry)) {
+ error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
+ dput(new_dentry);
+ }
+ up(&nd.dentry->d_inode->i_sem);
+out_release:
+ path_release(&nd);
+out:
+ path_release(&old_nd);
+exit:
+ putname(to);
+
+ return error;
+}
+
+/*
+ * The worst of all namespace operations - renaming directory. "Perverted"
+ * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
+ * Problems:
+ * a) we can get into loop creation. Check is done in is_subdir().
+ * b) race potential - two innocent renames can create a loop together.
+ * That's where 4.4 screws up. Current fix: serialization on
+ * sb->s_vfs_rename_sem. We might be more accurate, but that's another
+ * story.
+ * c) we have to lock _three_ objects - parents and victim (if it exists).
+ * And that - after we got ->i_sem on parents (until then we don't know
+ * whether the target exists). Solution: try to be smart with locking
+ * order for inodes. We rely on the fact that tree topology may change
+ * only under ->s_vfs_rename_sem _and_ that parent of the object we
+ * move will be locked. Thus we can rank directories by the tree
+ * (ancestors first) and rank all non-directories after them.
+ * That works since everybody except rename does "lock parent, lookup,
+ * lock child" and rename is under ->s_vfs_rename_sem.
+ * HOWEVER, it relies on the assumption that any object with ->lookup()
+ * has no more than 1 dentry. If "hybrid" objects will ever appear,
+ * we'd better make sure that there's no link(2) for them.
+ * d) some filesystems don't support opened-but-unlinked directories,
+ * either because of layout or because they are not ready to deal with
+ * all cases correctly. The latter will be fixed (taking this sort of
+ * stuff into VFS), but the former is not going away. Solution: the same
+ * trick as in rmdir().
+ * e) conversion from fhandle to dentry may come in the wrong moment - when
+ * we are removing the target. Solution: we will have to grab ->i_sem
+ * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
+ * ->i_sem on parents, which works but leads to some truely excessive
+ * locking].
+ */
+int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ int error = 0;
+ struct inode *target;
+
+ /*
+ * If we are going to change the parent - check write permissions,
+ * we'll need to flip '..'.
+ */
+ if (new_dir != old_dir) {
+ error = permission(old_dentry->d_inode, MAY_WRITE, NULL);
+ if (error)
+ return error;
+ }
+
+ error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (error)
+ return error;
+
+ target = new_dentry->d_inode;
+ if (target) {
+ down(&target->i_sem);
+ dentry_unhash(new_dentry);
+ }
+ if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
+ error = -EBUSY;
+ else
+ error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (target) {
+ if (!error)
+ target->i_flags |= S_DEAD;
+ up(&target->i_sem);
+ if (d_unhashed(new_dentry))
+ d_rehash(new_dentry);
+ dput(new_dentry);
+ }
+ if (!error) {
+ d_move(old_dentry,new_dentry);
+ security_inode_post_rename(old_dir, old_dentry,
+ new_dir, new_dentry);
+ }
+ return error;
+}
+
+int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ struct inode *target;
+ int error;
+
+ error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (error)
+ return error;
+
+ dget(new_dentry);
+ target = new_dentry->d_inode;
+ if (target)
+ down(&target->i_sem);
+ if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
+ error = -EBUSY;
+ else
+ error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (!error) {
+ /* The following d_move() should become unconditional */
+ if (!(old_dir->i_sb->s_type->fs_flags & FS_ODD_RENAME))
+ d_move(old_dentry, new_dentry);
+ security_inode_post_rename(old_dir, old_dentry, new_dir, new_dentry);
+ }
+ if (target)
+ up(&target->i_sem);
+ dput(new_dentry);
+ return error;
+}
+
+int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ int error;
+ int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
+
+ if (old_dentry->d_inode == new_dentry->d_inode)
+ return 0;
+
+ error = may_delete(old_dir, old_dentry, is_dir);
+ if (error)
+ return error;
+
+ if (!new_dentry->d_inode)
+ error = may_create(new_dir, new_dentry, NULL);
+ else
+ error = may_delete(new_dir, new_dentry, is_dir);
+ if (error)
+ return error;
+
+ if (!old_dir->i_op || !old_dir->i_op->rename)
+ return -EPERM;
+
+ DQUOT_INIT(old_dir);
+ DQUOT_INIT(new_dir);
+
+ if (is_dir)
+ error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
+ else
+ error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
+ if (!error) {
+ if (old_dir == new_dir)
+ inode_dir_notify(old_dir, DN_RENAME);
+ else {
+ inode_dir_notify(old_dir, DN_DELETE);
+ inode_dir_notify(new_dir, DN_CREATE);
+ }
+ }
+ return error;
+}
+
+static inline int do_rename(const char * oldname, const char * newname)
+{
+ int error = 0;
+ struct dentry * old_dir, * new_dir;
+ struct dentry * old_dentry, *new_dentry;
+ struct dentry * trap;
+ struct nameidata oldnd, newnd;
+
+ error = path_lookup(oldname, LOOKUP_PARENT, &oldnd);
+ if (error)
+ goto exit;
+
+ error = path_lookup(newname, LOOKUP_PARENT, &newnd);
+ if (error)
+ goto exit1;
+
+ error = -EXDEV;
+ if (oldnd.mnt != newnd.mnt)
+ goto exit2;
+
+ old_dir = oldnd.dentry;
+ error = -EBUSY;
+ if (oldnd.last_type != LAST_NORM)
+ goto exit2;
+
+ new_dir = newnd.dentry;
+ if (newnd.last_type != LAST_NORM)
+ goto exit2;
+
+ trap = lock_rename(new_dir, old_dir);
+
+ old_dentry = lookup_hash(&oldnd.last, old_dir);
+ error = PTR_ERR(old_dentry);
+ if (IS_ERR(old_dentry))
+ goto exit3;
+ /* source must exist */
+ error = -ENOENT;
+ if (!old_dentry->d_inode)
+ goto exit4;
+ /* unless the source is a directory trailing slashes give -ENOTDIR */
+ if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
+ error = -ENOTDIR;
+ if (oldnd.last.name[oldnd.last.len])
+ goto exit4;
+ if (newnd.last.name[newnd.last.len])
+ goto exit4;
+ }
+ /* source should not be ancestor of target */
+ error = -EINVAL;
+ if (old_dentry == trap)
+ goto exit4;
+ new_dentry = lookup_hash(&newnd.last, new_dir);
+ error = PTR_ERR(new_dentry);
+ if (IS_ERR(new_dentry))
+ goto exit4;
+ /* target should not be an ancestor of source */
+ error = -ENOTEMPTY;
+ if (new_dentry == trap)
+ goto exit5;
+
+ error = vfs_rename(old_dir->d_inode, old_dentry,
+ new_dir->d_inode, new_dentry);
+exit5:
+ dput(new_dentry);
+exit4:
+ dput(old_dentry);
+exit3:
+ unlock_rename(new_dir, old_dir);
+exit2:
+ path_release(&newnd);
+exit1:
+ path_release(&oldnd);
+exit:
+ return error;
+}
+
+asmlinkage long sys_rename(const char __user * oldname, const char __user * newname)
+{
+ int error;
+ char * from;
+ char * to;
+
+ from = getname(oldname);
+ if(IS_ERR(from))
+ return PTR_ERR(from);
+ to = getname(newname);
+ error = PTR_ERR(to);
+ if (!IS_ERR(to)) {
+ error = do_rename(from,to);
+ putname(to);
+ }
+ putname(from);
+ return error;
+}
+
+int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
+{
+ int len;
+
+ len = PTR_ERR(link);
+ if (IS_ERR(link))
+ goto out;
+
+ len = strlen(link);
+ if (len > (unsigned) buflen)
+ len = buflen;
+ if (copy_to_user(buffer, link, len))
+ len = -EFAULT;
+out:
+ return len;
+}
+
+/*
+ * A helper for ->readlink(). This should be used *ONLY* for symlinks that
+ * have ->follow_link() touching nd only in nd_set_link(). Using (or not
+ * using) it for any given inode is up to filesystem.
+ */
+int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+ struct nameidata nd;
+ int res;
+ nd.depth = 0;
+ res = dentry->d_inode->i_op->follow_link(dentry, &nd);
+ if (!res) {
+ res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
+ if (dentry->d_inode->i_op->put_link)
+ dentry->d_inode->i_op->put_link(dentry, &nd);
+ }
+ return res;
+}
+
+int vfs_follow_link(struct nameidata *nd, const char *link)
+{
+ return __vfs_follow_link(nd, link);
+}
+
+/* get the link contents into pagecache */
+static char *page_getlink(struct dentry * dentry, struct page **ppage)
+{
+ struct page * page;
+ struct address_space *mapping = dentry->d_inode->i_mapping;
+ page = read_cache_page(mapping, 0, (filler_t *)mapping->a_ops->readpage,
+ NULL);
+ if (IS_ERR(page))
+ goto sync_fail;
+ wait_on_page_locked(page);
+ if (!PageUptodate(page))
+ goto async_fail;
+ *ppage = page;
+ return kmap(page);
+
+async_fail:
+ page_cache_release(page);
+ return ERR_PTR(-EIO);
+
+sync_fail:
+ return (char*)page;
+}
+
+int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+ struct page *page = NULL;
+ char *s = page_getlink(dentry, &page);
+ int res = vfs_readlink(dentry,buffer,buflen,s);
+ if (page) {
+ kunmap(page);
+ page_cache_release(page);
+ }
+ return res;
+}
+
+int page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
+{
+ struct page *page;
+ nd_set_link(nd, page_getlink(dentry, &page));
+ return 0;
+}
+
+void page_put_link(struct dentry *dentry, struct nameidata *nd)
+{
+ if (!IS_ERR(nd_get_link(nd))) {
+ struct page *page;
+ page = find_get_page(dentry->d_inode->i_mapping, 0);
+ if (!page)
+ BUG();
+ kunmap(page);
+ page_cache_release(page);
+ page_cache_release(page);
+ }
+}
+
+int page_symlink(struct inode *inode, const char *symname, int len)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct page *page = grab_cache_page(mapping, 0);
+ int err = -ENOMEM;
+ char *kaddr;
+
+ if (!page)
+ goto fail;
+ err = mapping->a_ops->prepare_write(NULL, page, 0, len-1);
+ if (err)
+ goto fail_map;
+ kaddr = kmap_atomic(page, KM_USER0);
+ memcpy(kaddr, symname, len-1);
+ kunmap_atomic(kaddr, KM_USER0);
+ mapping->a_ops->commit_write(NULL, page, 0, len-1);
+ /*
+ * Notice that we are _not_ going to block here - end of page is
+ * unmapped, so this will only try to map the rest of page, see
+ * that it is unmapped (typically even will not look into inode -
+ * ->i_size will be enough for everything) and zero it out.
+ * OTOH it's obviously correct and should make the page up-to-date.
+ */
+ if (!PageUptodate(page)) {
+ err = mapping->a_ops->readpage(NULL, page);
+ wait_on_page_locked(page);
+ } else {
+ unlock_page(page);
+ }
+ page_cache_release(page);
+ if (err < 0)
+ goto fail;
+ mark_inode_dirty(inode);
+ return 0;
+fail_map:
+ unlock_page(page);
+ page_cache_release(page);
+fail:
+ return err;
+}
+
+struct inode_operations page_symlink_inode_operations = {
+ .readlink = generic_readlink,
+ .follow_link = page_follow_link_light,
+ .put_link = page_put_link,
+};
+
+EXPORT_SYMBOL(__user_walk);
+EXPORT_SYMBOL(follow_down);
+EXPORT_SYMBOL(follow_up);
+EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
+EXPORT_SYMBOL(getname);
+EXPORT_SYMBOL(lock_rename);
+EXPORT_SYMBOL(lookup_hash);
+EXPORT_SYMBOL(lookup_one_len);
+EXPORT_SYMBOL(page_follow_link_light);
+EXPORT_SYMBOL(page_put_link);
+EXPORT_SYMBOL(page_readlink);
+EXPORT_SYMBOL(page_symlink);
+EXPORT_SYMBOL(page_symlink_inode_operations);
+EXPORT_SYMBOL(path_lookup);
+EXPORT_SYMBOL(path_release);
+EXPORT_SYMBOL(path_walk);
+EXPORT_SYMBOL(permission);
+EXPORT_SYMBOL(unlock_rename);
+EXPORT_SYMBOL(vfs_create);
+EXPORT_SYMBOL(vfs_follow_link);
+EXPORT_SYMBOL(vfs_link);
+EXPORT_SYMBOL(vfs_mkdir);
+EXPORT_SYMBOL(vfs_mknod);
+EXPORT_SYMBOL(generic_permission);
+EXPORT_SYMBOL(vfs_readlink);
+EXPORT_SYMBOL(vfs_rename);
+EXPORT_SYMBOL(vfs_rmdir);
+EXPORT_SYMBOL(vfs_symlink);
+EXPORT_SYMBOL(vfs_unlink);
+EXPORT_SYMBOL(dentry_unhash);
+EXPORT_SYMBOL(generic_readlink);
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-02 01:54:39 +0000